1. Field of the Invention
This invention relates to laminates and foam filled sheet products, both decorative and structural, and more particularly it relates to structurally rigid, optionally glass fiber reinforced, sheets of foam, which are particularly useful in thermal insulating applications. It also relates to a method for forming such a product.
2. Description of the Prior Art
Laminated rigid foam panels are widely used in the building and construction industry as sound and thermal insulating materials and as non-load bearing structural members. These laminated articles having a core of rigid foam can be made continuously or batchwise in a mold. The process of continuous or semicontinuous lamination usually involves deposition of a foam-forming plastics mixture onto a facing sheet(s) and bringing a second sheet(s) into contact with the mixture before it sets and sometimes before it foams.
The facing sheet(s) reduce the risk of physical damage to the foam and can aid significantly in maintaining the insulation value of the foam. Facers commercially used to protect foam products include aluminum foil, felt, glass and kraft paper in monolayers or laminates. Conveniently, both for economy and ease of handling, the facing sheets are often made of relatively inexpensive flexible materials, such as kraft and aluminum foil, which can be fed from rolls.
While use of impermeable aluminum foil provides an especially high insulation value, a disadvantage associated with its use alone as a facer stems from its fragility, which can result, e.g., in foil breakage during foamboard manufacture. While improved facer toughness can be achieved through the use of fibrous facers, such as conventional medium or heavy kraft papers or glass mats, these facers are no match for aluminum foil at providing a barrier against gas penetration. The porosity of fibrous facers allows excessive exposure of the foam material to air with the consequent opportunity for air infiltration into the foam. As is well known in the industry, the thermal conductivity (k-factor) of insulating boards containing fluorocarbon gas is substantially increased where some means is not provided to prevent such air infiltration into the cells of the foam insulation.
It would be highly desirable if a foam insulation board could be produced with facers which have outstanding toughness, surpassing conventional facing materials, and contribute overall good properties to the foam board.